Containers using resin materials such as polyethylene terephthalate (PET) have found a wider variety of uses, and those of a wide-mouthed type have been available for food preservation. Preforms for such a type of container are markedly insufficient in alignment properties in comparison with preforms for beverage bottles. Causes for this marked insufficiency include, for example, neck shapes so diverse as to have no diameter of curvature in an inwardly convex section of a trunk below a support ring; shapes of very small dimensions; and large mouth diameters and shapes at diameter/overall height≈1, so that the center of gravity is close to the middle. Because of the relatively heavy weight, moreover, surface flaws are apt to occur.
With a blow molding machine adopting a 2-stage process, the above-mentioned preforms need to be aligned and fed.
Among alignment apparatuses for such purposes are roller type aligning machines, vibration bowl type aligning machines, and rotating disk type aligning machines. The roller type aligning machine, however, cannot sufficiently deal with diverse wide-mouthed preforms. Concretely, narrow-mouthed preforms for beverage containers have a neck shape (support ring) standardized, and their trunk shape is slender and easily supportable in a single direction (vertical direction) on aligning rollers. Wide-mouthed preforms for food preservation, by contrast, have a neck shape ranging in many types and wide varieties, without being standardized. Their support rings are often small compared with the diameter of the preform. Furthermore, the trunk is nearly bowl-shaped, and its center of gravity is located near the center of the preform. Thus, the preforms are difficult to support on the aligning rollers in a single direction. Besides, the vibration bowl type aligning machine poses the problems that it is relatively low in the capacity to align and supply preforms and is apt to cause surface flaws. On the other hand, the rotating disk type aligning machine is described, for example, in Patent Document 1.